Alcohol Intoxication Signs and Symptoms

The effects of alcohol vary widely from person to person. Several factors can account for obvious differences in how certain amounts of alcohol can affect one person more than another. These factors also affect the particular signs and symptoms the person may exhibit to indicate alcohol intoxication.

Major factors accounting for this variation in signs and symptoms:

Prior experience with alcohol: A longtime, heavy drinker may achieve blood alcohol concentration levels that would kill the average casual drinker. Conversely, a novice drinker may have severe symptoms with the ingestion of a moderate amount of alcohol. As a person's drinking increases, his/her liver will increase its capacity to metabolize alcohol. In addition, the brain of a heavy drinker becomes used to frequent, even constant, high blood alcohol concentrations. This habituation in a heavy drinker can backfire if this person suddenly stops drinking. The person may go into alcohol withdrawal and develop seizures or a condition called delirium tremens (DTs).

Taking medications: The effects of alcohol are enhanced if a person is taking other prescription medications, especially those of the sedative class such as sleeping pills or anti-anxiety medications. A person who is not habituated to either alcohol or sedatives may experience serious harm, or even death, if taking prescribed doses. Together, they can be a deadly combination. A person may be taking medications prescribed by a doctor or over-the-counter medications, and may not know about these unintended consequences.

Medical conditions: The presence of a wide variety of medical conditions may affect how a person reacts to alcohol.

Smell of alcohol on the breath: There is a very poor correlation between the strength of the smell of alcohol on the breath and the blood alcohol concentration. Pure alcohol has very little smell. It is the metabolism of other substances in alcoholic beverages that produces most of the smell. This explains why a person who drinks large amounts of high-proof vodka (a more pure form of alcohol) may have only a faint smell of alcohol on the breath. On the other hand, a person who drinks a modest amount of beer may have a strong smell of alcohol on the breath.

Scale of effects: In the average social drinker (defined as someone who drinks no more than two standard drinks per day), there is a rough correlation between blood alcohol concentration and how the person acts.

Blood alcohol concentration. Blood alcohol concentration commonly is expressed in milligrams per deciliter (mg/dL). Using this measure, 100 mg/dL roughly is equal to one part alcohol in 1000 parts of water (or blood). Consequently, 100 mg/dL would be equal to a 0.1% concentration. In most states, 100 mg/dL represents the threshold concentration above which a person is legally intoxicated when operating a motor vehicle.

To find out more about blood alcohol concentration and how it affects a person, go to the Blood Alcohol Educator Web site of the Century Council and the University of Illinois.

TThe following scale details the expected effects of alcohol at various blood alcohol concentrations. There is a tremendous variation from person to person, and not all people exhibit all the effects. This scale would apply to a typical social drinker:

500 mg/dL: Death possible, either from cessation of breathing, excessively low blood pressure, or vomit entering the lungs without the presence of the protective reflex to cough it out

Other conditions that look like alcohol intoxication: It is important to recognize the symptoms of alcohol intoxication not only to confirm the presence and severity of the alcohol effect, but also to be able to differentiate the symptoms from other conditions that may coexist, mimic, or mask the symptoms of alcohol intoxication.

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